Down on Vitamin D? It Could Be the Cause of Chronic Inflammation

Summary: Study reveals a direct link between vitamin D deficiency and chronic inflammation. Researchers suggest boosting vitamin D in those with a deficiency may help to reduce inflammation.

Source: University of South Australia

Inflammation is an essential part of the body’s healing process. But when it persists, it can contribute to a wide range of complex diseases including type 2 diabetes, heart disease, and autoimmune diseases.

Now, world-first genetic research from the University of South Australia shows a direct link between low levels of vitamin D and high levels of inflammation, providing an important biomarker to identify people at higher risk of or severity of chronic illnesses with an inflammatory component.

The study examined the genetic data of 294 ,970 participants in the UK Biobank, using Mendelian randomization to show the association between vitamin D and C-reactive protein levels, an indicator of inflammation.

Lead researcher, UniSA’s Dr Ang Zhou, says the findings suggest that boosting vitamin D in people with a deficiency may reduce chronic inflammation.

“Inflammation is your body’s way of protecting your tissues if you’ve been injured or have an infection,” Dr Zhou says.

“High levels of C-reactive protein are generated by the liver in response to inflammation, so when your body is experiencing chronic inflammation, it also shows higher levels of C-reactive protein.

“This study examined vitamin D and C-reactive proteins and found a one-way relationship between low levels of vitamin D and high levels of C-reactive protein, expressed as inflammation.

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There’s a direct link between low levels of vitamin D and high levels of inflammation. Credit: Rebecca Wood

“Boosting vitamin D in people with deficiencies may reduce chronic inflammation, helping them avoid a number of related diseases.”

Supported by the National Health and Medical Research Council and published in the International Journal of Epidemiology the study also raises the possibility that having adequate vitamin D concentrations may mitigate complications arising from obesity and reduce the risk or severity of chronic illnesses with an inflammatory component, such as CVDs, diabetes, and autoimmune diseases.

Senior investigator and Director of UniSA’s Australian Centre for Precision Health, Professor Elina Hyppönen, says these results are important and provide an explanation for some of the controversies in reported associations with vitamin D.

“We have repeatedly seen evidence for health benefits for increasing vitamin D concentrations in individuals with very low levels, while for others, there appears to be little to no benefit.” Prof Hyppönen says. 

“These findings highlight the importance of avoiding clinical vitamin D deficiency, and provide further evidence for the wide-ranging effects of hormonal vitamin D.”

About this inflammation research news

Author: Annabel Mansfield
Source: University of South Australia
Contact: Annabel Mansfield – University of South Australia
Image: The image is credited to Rebecca Wood

Original Research: Open access.
Vitamin D deficiency and C-reactive protein: a bidirectional Mendelian randomization study” by Elina Hyppönen et al. International Journal of Epidemiology


Vitamin D deficiency and C-reactive protein: a bidirectional Mendelian randomization study


Low vitamin D status is often associated with systemic low-grade inflammation as reflected by elevated C-reactive protein (CRP) levels. We investigated the causality and direction of the association between vitamin D status and CRP using linear and non-linear Mendelian randomization (MR) analyses.


MR analyses were conducted using data from 294 970 unrelated participants of White-British ancestry from the UK Biobank. Serum 25-hydroxyvitamin D [25(OH)D] and CRP concentrations were instrumented using 35 and 46 genome-wide significant variants, respectively.


In non-linear MR analysis, genetically predicted serum 25(OH)D had an L-shaped association with serum CRP, where CRP levels decreased sharply with increasing 25(OH)D concentration for participants within the deficiency range (<25 nmol/L) and levelled off at ∼50 nmol/L of 25(OH)D (Pnon-linear = 1.49E-4). Analyses using several pleiotropy-robust methods provided consistent results in stratified MR analyses, confirming the inverse association between 25(OH)D and CRP in the deficiency range (P = 1.10E-05) but not with higher concentrations. Neither linear or non-linear MR analysis supported a causal effect of serum CRP level on 25(OH)D concentration (Plinear = 0.32 and Pnon-linear = 0.76).


The observed association between 25(OH)D and CRP is likely to be caused by vitamin D deficiency. Correction of low vitamin D status may reduce chronic inflammation.

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  1. Don’t waste your money on supplements as decades long studies proved that humans can’t absorb vitamin D and C from supplements. A quick internet search will give you all the proof you want.

  2. Humans create much of their own “D” which is not really a vitamin, but a hormone. This is probably in proportion to their time spent in the sun or exposure to sunlight. So, I assume that “D” is very necessary to our health and existence. This would lead me to believe that a person who is locked up or hidden from sunlight would be subject to any number of afflictions and diseases. Thus, “D” is required and not subject to over-use except in extreme cases.

    1. Yes, a lack of certain vitamins can cause rickets or scurvy or beri beri. In third world countries, this is particularly true. And in the past especially in war time soldiers suffered from a lack of Vitamin D.

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